All horoscopes have three main components: planets, signs, and houses. The planets show what is happening, the signs show how it's happening, and the houses show where it's happening. What follows is a brief overview of the planets and what they represent.

The term planet refers to the Sun, Moon, and the other bodies in the solar system, which include Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Of course, the Sun and Moon are not really planetary bodies, but, for ease, are often referred to as such. Each planet represents a function in the human personality or psyche, and are grouped into two categories: the personal planets, which comprise Sun, Moon, Mercury, Venus, and Mars, and the outer planets, Jupiter through Pluto. The term "outer planets" is more often applied to Uranus, Neptune, and Pluto, whereas Jupiter and Saturn are considered the "social" planets.

The personal planets move more quickly through the zodiac, accounting for significant differences between the horoscopes of individuals born only days apart. For example, the Moon moves through all 12 signs in less than 29 days, and Mars will travel through the entire 12 signs in 2 years. In contrast, the outer planets take much longer to move through the signs. Jupiter takes a year to move through one sign, and the outer planets take considerably longer. Because of their slow movement, the outer planets have more of a generational influence.

A planet's expression is determined by its sign and house placement. Everyone has a Mercury – we all possess the part of the psyche it symbolizes. But not everyone has Mercury in Taurus in the 4th house. Once you are familiar with the functions of each planet, you can then discover how those functions express themselves (sign placement) and in what area of life they are most likely to manifest (house placement).

Now let's get right into the nuts and bolts and take a look at what each planet represents. Keep in mind that the following definitions are very brief and generalized. As with any area of astrology, there are many other layers of interpretation and meaning that are useful, valid, and important. Don't let your exploration stop here!

The Sun in the horoscope represents the basic identity, the life purpose and the will to exist. Just as the movements of the planets reflect human affairs, the planets in the horoscope are also reflections of specific parts of the Solar purpose. An individual with Sun in Leo, for example, may have full creative self-expression as his or her life purpose, and this purpose will be further described and modified by both the placements of the other planets and their angular relationships, or aspects, to the Sun.

The Moon, which reflects the light of the Sun, is our personal reservoir or container of life experiences, the colored glasses through which we perceive our world. It is a way of being and of relating to life that feels more natural and comfortable. Although the Moon does not represent emotions per se, it is connected with the emotions and with memory to the extent that we ascribe emotions to our experiences. To put it another way, the Moon is like a photo album containing the many pictures of our lives. When we look at these pictures, they evoke certain feeling states and emotions. Someone with Moon in Pisces may experience their world in a highly imaginitive way, while a Capricorn Moon may relate to their environment in a more rational, objective manner.

Mercury relates to the principle of intellect and the ability of an individual to perceive and relate to other individuals or objects as different from themselves. It is therefore connected to communication, language, and symbol. Unlike the Moon, which assigns emotion to experience, Mercury is neutral, acting only to bridge the space between the individual and other beings.

Venus acts as an internal barometer or thermostat, giving feedback about what is or isn't comfortable and desirable to the individual, and is also a powerful indicator of what a person values. It denotes appreciation for aesthetically pleasing forms, particularly those that enhance the individual's sense of internal harmony. It generally imparts information about what a person grooves on.

Mars's function is to act on the desires and needs described by Venus and other chart factors. It symbolizes assertion, action, and the focused use of will, and is associated with the survival instinct. Its purpose is to maintain the individual's sense of separateness, and to generate self-expression. More negatively, it can manifest as unnecessary aggression and willfulness. Mars in the fire sign Aries may express itself in a feisty and impulsive and/or defiant manner, while Mars in Capricorn will typically be more reserved, using its energy to protect its material interests and meet its goals. Jupiter symbolizes the principle of expansion and growth and describes how the individual integrates him- or herself into society and personal environment. It also represents the desire to grow, to learn and to incorporate new information and experience. Its position shows the area of life where we may positively benefit from our inherent qualities and talents, and, perhaps more importantly, from our ability to recognize opportunities as they become available.

Saturn indicates the principles of form, disciplined action, and gradual development. It often describes the rules a person has established for him- or herself, and/or the external limits and restrictions that are necessarily imposed for the growth of individual consciousness. These limitations can loom as serious obstacles, and a person will often feel fearful and inadequate in the areas of life that Saturn affects in the birth chart. The goal is to develop confidence and stability where necessary.

The function of Uranus is a metaphoric awakening of the individual through a psychological breakthrough, an unexpected event, or a departure from old forms. It represents conscious shock, the ability of the individual to break through to new levels or realms of understanding or consciousness.

Neptune's role is that of dissolving psychic boundaries, bringing about a sense of oneness with the universe.

Finally, Pluto acts by completely overhauling a form – a part of the psyche or an area of life – by destroying it and then recreating it. It signifies the area of life where a person will undergo deep, transformative change. As previously mentioned, Uranus, Neptune, and Pluto move very slowly, staying in the same sign for years. For this reason, their effects are not felt as personally, but tend to impact on a generational level. For example, all of those born with Uranus in Leo may naturally develop and/or be drawn to original, innovative, and unusual creative expressions.

Chiron and the asteroids are worthy of study, but we don't have the space to get into them here.

RESOURCES FOR FURTHER STUDY

There are so many good books on the planets we couldn't list them all ... but here are a few we have found especially useful:

Joan McEvers, editor, Planets: The Astrological Tools; Llewellyn Publications. This book is part of Llewellyn's New World Astrology Series.